FIV2018 Paper Management System, FIV2018 Conference

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Experimental Investigation of Cavitation-Induced Acoustic Noise from Marine Propellers
Dylan Iverson, Duncan William McIntyre, Mostafa Rahimpour, Giorgio Tani, Fabiana Miglianti, Michele Viviani, Zuomin Dong, Peter Oshkai

Last modified: 2018-06-25

Abstract


Previous investigations of seafaring ship acoustics identified propeller cavitation as a dominant source of radiated underwater noise. The ship-induced acoustic noise can be treated as a measure of environmental impact of marine transportation industry. Quantitative prediction of emitted noise levels requires detailed characterization of cavitation regimes associated with operation of marine propellers. We conducted an experimental campaign in a pressurized cavitation tunnel, following the experimental standards of the International Towing Tank Conference (ITTC). The experiments were designed to reproduce various cavitation regimes that are expected to occur during operation of a typical four-bladed controllable-pitch propeller of a tanker ship. The measurements were conducted under steady inflow conditions, in order to provide a first set of simplified cases for validation of numerical methodologies, before moving to more complex behind hull conditions. We obtained stroboscopic photographic images of the cavitation event, measurements of propeller loads, and high-resolution acoustic pressure levels across a broad frequency spectrum. Ambient pressure, inflow velocity, shaft rotation rate, and propeller blade pitch were systematically varied to achieve an insightful range of experimental conditions. The distinct regimes of bubble cavitation, sheet cavitation, and tip vortex cavitation were created experimentally in varying combinations, along with a reference case of cavitation suppression. For each considered cavitation regime, we identified the corresponding dominant frequencies and acoustic noise levels. The experiments will validate the propeller cavitation noise model that is used to guide ship hybrid electric propulsion system design and operation control to reduce sip induced ocean noise.


Keywords


Cavitation; Marine propellers; Acoustics

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